Resilient device for urging a magnetic record



1960 M. HEITNER 2,935,574

RESILIENT DEVICE FOR URGING A MAGNETIC RECGRD Filed April 12, 1955 INVENTOR MANFRED HEITNER AGENT United dtates Patent 2,935,574 RESILIENT DEVICE FOR URGING A MAGNETIC RECORD Manfred Heitner, Eindhoven, Netherlands, assignor, by

mesne assignments, to North 'American Philips Company, Inc., New York, N.Y., a corporation of Delaware Application April 12, 1955, Serial No. 500,934 Claims priority, application Netherlands April 28, 1954 4 Claims. (Cl. 179-1002) The invention relates to a resilient member for tightening a magnetic record carrier against a rigid element of an apparatus associated with the carrier, for example against the magnet head.

It is already known to have such a resilient member constituted by a blade spring which exerts the pressure by way of a body for example of felt. Such a pressure has an advantage that if the member urges the carrier against the magnet head the distance of the carrier from the gap of the magnet head remains constant to a great extent, which is of great importance for the recording and reproducing process.

Moreover, the pressure may be utilized for keeping the carrier taut by choosing the contact area of the resilient member to lie on the other side of the magnet head than the side where the driving reel or tone roller is provided. If, in this case, the carrier travels with a certain curvature over the magnet head, the mechanical tension of the magnet head, the mechanical tension of the carrier thus obtained will be favorable to the recording and reproducing process due to the constancy of the distance between carrier and gap.

. During operation the carrier will be drawn along the body of soft material, for example felt. This material is provided between the carrier and the resilient member, this member being usually made of elastic metal in order to avoid damage to the carrier.

Under certain conditions, for example if the carrier is very dry, a series of discontinuities are produced in the friction between carrier and resilient member which may give rise to resonance of the member. Such a resonating body may produce not only acoustical energy in the form of a whistle, but also a magnetic recording of such high frequencies on the carrier. It will be obvious that all these phenomena are to be regarded as disadvantages in the recording and reproduction of the magnetic records.

In order to overcome the aforesaid disadvantages, the resilient member according to the invention comprises two or more blade springs between which damping material is provided. Although the use of the damping properties of certain materials is known for avoiding the resonance of bodies, the invention is based on the recognition of the fact that it is found to be possible to obviate the frequent occurrence of relaxation oscillations which is a typical difiiculty with magnetic recording and reproduction by increasing the number of blade springs and by interconnecting them by damping material. In a particular embodiment of the resilient member according to the invention the blade springs extend parallel to one another and are secured at one end to a common supporting body.

The invention will be described with reference to a few embodiments.

Fig. 1 shows a resilient member according to the invention, in which the two blade springs lie in one plane and both of them urge the tape against the magnet head and Fig. 2 shows a sectional view of the blade springs taken on the line II-II of Fig. 1.

Fig. 3 shows a further embodiment, in which the two blade springs are secured to one another by way of damping material.

Referring more particularly to the drawings, Fig. 1 shows a resilient member according to the invention for urging a magnetic record carrier 1 against the magnet head 2 of an apparatus associated with the carrier. The head is shown in a front view together with the gap. The resilient member comprises two blade springs 3 and 4, between which damping material 5, for example polyvinyl chloride is provided (see also Fig. 2.). The blade springs, 3 and 4 are parallel to one another and are secured at one end to a common supporting body 6, where the body is also secured to the housing of the apparatus. At the other end of the blade springs provision is made of felt, which furthers a sliding contact between the metal blade springs of for example brass and the carrier. It is of course, also possible to secure the two blade springs separately to the apparatus.

Fig. 3 shows a further embodiment of a resilient member according to the invention in a lateral view. The resilient member comprises two blade springs 7 and 8, which are secured to one another on their fiat surfaces via the damping layer 9. At one end of the blade spring 8 provision is made of a block of felt 10, through which the resilient element exerts the pressure on the carrier. I

At 11 the resilient member is clamped tight.

While I have shown and described the preferred em-- bodiment of my invention, it will be understood that the latter may be embodied otherwise than as herein specifically illustrated or described and that in the illustrated embodiment certain changes in the details of construction and in the arrangement of parts may be made without departing from the underlying idea or principle of the invention within the scope of the appended claims.

What is claimed is:

l, A magnetic head assembly including a magnetic record carrier comprising a resilient device for urging said magnetic record carrier into engagement with said magnetic head, said resilient device comprising a supporting body, at least two spaced blade springs secured at adiacent ends to said supporting body, said spaced blade springs lying in the same plane, and a damping material positioned between and engaging at least a resilient part of each of said blade springs, the free ends of said blade springs engaging with pressure said magnetic carmen 2. A magnetic head assembly including a magnetic record carrier comprising a resilient device for urging said magnetic record carrier into engagement with said magnetic head, said resilient device comprising a supporting body, at least two blade springs, each of said blade springs being mounted with one end thereof in said supporting body in parallel'relationship to the other of said blade springs, and a damping material positioned between and engaging at least a resilient part of each of said blade springs, the other end of each of said blade springs engaging with pressure said magnetic record carrier.

3. A magnet head assembly as set forth in claim 2 wherein said damping material is polyvinyl chloride.

4. A magnet head assembly as set forth in claim 2 further comprising a felt block secured to the other end of one of said blade springs for exerting pressure on said carrier.

References Cited in the file of this patent UNITED STATES PATENTS 2,559,105 Banning July 3, 1951 2,585,913 Camras Feb. 19, 1952 2,603,721 Camras July 15, 1952 2,772,135 Hollabaugh et al Nov. 27, 1956 

